U.S. patent number 5,981,077 [Application Number 08/861,953] was granted by the patent office on 1999-11-09 for image transfer sheet and image forming method therefor.
This patent grant is currently assigned to Ricoh Company, Ltd.. Invention is credited to Keishi Taniguchi.
United States Patent |
5,981,077 |
Taniguchi |
November 9, 1999 |
Image transfer sheet and image forming method therefor
Abstract
An image transfer sheet in which a releasing layer is formed on
at least one side of a substrate and an image transfer layer
including a self-crosslinkable polymer is formed on the releasing
layer. An image is formed on the image transfer layer by an
electrophotography method, a thermal transfer recording method or
the like, and then transferred onto an image receiving material.
The transferred image on the image receiving material has good
image qualities and good resistance to heat of iron and
washing.
Inventors: |
Taniguchi; Keishi (Susono,
JP) |
Assignee: |
Ricoh Company, Ltd. (Tokyo,
JP)
|
Family
ID: |
26458449 |
Appl.
No.: |
08/861,953 |
Filed: |
May 22, 1997 |
Foreign Application Priority Data
|
|
|
|
|
May 29, 1996 [JP] |
|
|
8-135434 |
May 12, 1997 [JP] |
|
|
9-120974 |
|
Current U.S.
Class: |
428/447; 428/448;
428/482 |
Current CPC
Class: |
B41M
5/38257 (20130101); B41M 5/52 (20130101); B41M
5/0256 (20130101); B41M 7/0027 (20130101); B41M
7/009 (20130101); D06P 5/003 (20130101); B41M
5/504 (20130101); B41M 5/506 (20130101); B41M
5/5254 (20130101); Y10T 428/31663 (20150401); Y10T
428/31794 (20150401) |
Current International
Class: |
B41M
7/00 (20060101); B41M 5/52 (20060101); B41M
5/50 (20060101); D06P 5/24 (20060101); B41M
5/00 (20060101); B32B 009/04 () |
Field of
Search: |
;428/447,448,482 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
5260139 |
November 1993 |
Shiraishi et al. |
5721086 |
February 1998 |
Emslander et al. |
|
Primary Examiner: Chapman; Mark
Attorney, Agent or Firm: Cooper & Dunham LLP
Claims
What is claimed is:
1. An image transfer sheet in which a releasing layer is formed on
at least one side of a substrate and an image transfer layer
comprising a self-crosslinkable polymer is formed on the releasing
layer and which is useful for an image forming method in which an
image formed on the image transfer layer is transferred onto an
image receiving material together with the image transfer
layer.
2. The image transfer sheet of claim 1, wherein the releasing layer
comprises a silicone compound.
3. The image transfer sheet of claim 2, wherein the silicone
compound comprises a room temperature vulcanizing silicone
rubber.
4. The image transfer sheet of claim 1, wherein the
self-crosslinkable polymer comprises at least one of a methylol
group and an alkoxymethyl group.
5. The image transfer sheet of claim 4, wherein the
self-crosslinkable polymer comprises an ethylene-vinyl
acetate-acrylate copolymer having at least one of a methylol group
and an alkoxymethyl group.
6. The image transfer sheet of claim 1, wherein the
self-crosslinkable polymer comprises a self-crosslinkable polymer
having a glass transition temperature higher than or equal to
0.degree. C. and a self-crosslinkable polymer having a glass
transition temperature lower than 0.degree. C.
7. The image transfer sheet of claim 1, wherein said substrate has
two opposed sides, said releasing layer is formed on only one of
said sides, and a back coat layer is formed on the other of said
sides.
8. The image transfer sheet of claim 7, wherein the back coat layer
comprises a room-temperature vulcanizing silicone rubber.
9. The image transfer sheet of claim 1, wherein the
self-crosslinkable polymer comprises a self-crosslinkable polymer
having a molecular weight of from about 10,000 to about 500,000 and
a self-crosslinkable polymer having a molecular weight of from
about 10,000,000 to about 60,000,000.
10. An image forming method comprising the steps of:
providing an image transfer sheet in which a releasing layer is
formed on at least one side of a substrate and an image transfer
layer including a self-crosslinkable polymer is formed on the
releasing layer; and
forming an image on the image transfer layer.
11. The image forming method of claim 10, wherein the image is
formed of toner using electrophotography and fixed by at least one
of heat and pressure.
12. The image forming method of claim 10, wherein the image is
formed of at least one of a thermofusible ink and a sublimation dye
using thermal transfer recording.
13. The image forming method of claim 10, wherein the image forming
method further comprises an image transferring step in which the
image on the image transfer layer is transferred onto an image
receiving material.
14. The image forming method of claim 13, wherein the image on the
image transfer layer is transferred onto the image receiving
material upon application of heat and pressure.
15. The image forming method of claim 10, wherein the releasing
layer comprises a silicone compound.
16. The image forming method of claim 15, wherein the silicone
compound comprises a room temperature vulcanizing silicone
rubber.
17. The image forming method of claim 10, wherein the
self-crosslinkable polymer comprises at least one of a methylol
group and an alkoxymethyl group.
18. The image forming method of claim 17, wherein the
self-crosslinkable polymer comprises an ethylene-vinyl
acetate-acrylate copolymer having at least one of a methylol group
and an alkoxymethyl group.
19. The image forming method of claim 17, wherein the
self-crosslinkable polymer comprises a self-crosslinkable polymer
having a glass transition temperature higher than or equal to
0.degree. C. and a self-crosslinkable polymer having a glass
transition temperature lower than 0.degree. C.
20. The image transfer method of claim 10, wherein said substrate
has two opposed sides, said releasing layer is formed on only one
of said sides, and a back coat layer is formed on the other of said
sides.
21. The image transfer method of claim 20, wherein the back coat
layer comprises a room-temperature vulcanizing silicone rubber.
22. The image forming method of claim 17, wherein the
self-crosslinkable polymer comprises a self-crosslinkable polymer
having a molecular weight of from about 10,000 to about 500,000 and
a self-crosslinkable polymer having a molecular weight of from
about 10,000,000 to about 60,000,000.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image transfer sheet and an
image forming method therefor in which an image is formed on the
image transfer sheet by an image recording method, such as
electrophotography, thermal transfer recording, ink jet recording
or the like and the formed image on the image transfer sheet is
transferred onto an image receiving material, such as cloth,
canvas, plastics, paper, wood, leather, glass, china, metals or the
like.
2. Discussion of the Related Art
Recently, a variety of image forming apparatus have been developed
and utilized for copiers and printers for computers or the like.
The images formed with these image forming apparatus are not only
used for a purpose of reading or viewing, but also tried to be
applied for various new applications.
As one of these new applications of the images, a method is
proposed in which the images are transferred onto an image
receiving material, such as cloth, canvas, plastics, paper, wood,
leather, glass, china, metals or the like. This method is useful
for manufacturing a small lot of made-to-order goods having
original pictures thereon, such as T-shirts, sweat shirts, aprons,
jackets, cups, plates or stained glass and for duplicating of
pictures on canvas. Currently, since full color copiers are
developed and high quality full color images can easily be
obtained, the demand for this method is increasing more and
more.
Such an image transfer sheet that transfers toner images thereon
onto an above-mentioned image receiving material is discussed in
Japanese Laid-Open Patent Application No. 52-82509, incorporated
herein by this reference. In the patent application, an image
transfer sheet is disclosed in which an adhesive layer including an
adhesive material selected from the group consisting of silicone
and fluorine-containing polymers is formed on a substrate and an
image transfer layer including a specific polymer having a
relatively low melting point is formed on the adhesive layer. Toner
images are formed on the image transfer layer and the formed toner
images are then transferred onto an image receiving material
together with the image transfer layer which is softened when
heated to transfer the toner images. The specific examples of the
polymer having a relatively low melting point which are described
for use in the image transfer layer of the patent application are
the polymers selected from the group consisting of polyvinyl
chloride, polyvinyl acetate, polymethyl methacrylate, polyethyl
methacrylate, polybutyl methacrylate and polyvinylidene chloride
and the mixtures and the copolymers thereof. However, the adhesion
of these polymers to the above-mentioned image receiving materials
is insufficient, so that a problem occurs in which transferred
images on the image receiving materials are easily peeled from the
image receiving materials after several times of washing. In
addition, a problem also occurs in which transferred images are
destroyed or adhered to an iron when the image receiving material
bearing transferred images is ironed. This is because the
transferred images are melted or softened by the heat of the
iron.
Because of these reasons, a need exists for an image transfer sheet
which has good image receivability when an image is formed on the
image transfer sheet and good image transferability and fixability
when the image is transferred onto various receiving materials.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an
image transfer sheet which has good image receivability when an
image is formed on the image transfer sheet and good image
transferability and fixability when the image is transferred onto
various receiving materials.
Another object of the present invention is to provide an image
transfer sheet in which an image formed on the image transfer sheet
can easily be transferred onto various image receiving materials
without any complicated techniques even after the image transfer
sheet is cooled, which is useful for when it is desired that a
large image is transferred onto the image receiving materials.
Yet another object of the present invention is to provide an image
transfer sheet which can be manufactured without using organic
solvents, resulting in preventing environmental pollution and cost
effective manufacturing.
A further object of the present invention is to provide an image
transfer sheet having good feeding properties without jamming when
images are formed thereon in image forming apparatus.
To achieve such objects of the present invention, the present
invention contemplates the provision of an image transfer sheet in
which a releasing layer is formed on at least one side of a
substrate and an image transfer layer including a
self-crosslinkable polymer is formed on the releasing layer.
Preferably, the releasing layer includes a silicone compound, and
more preferably the silicone compound includes a room-temperature
vulcanizing silicone rubber.
In addition, the self-crosslinkable polymer preferably has a
methylol group and/or an alkoxymethyl group as a self-crosslinkable
component, and more preferably the self-crosslinkable polymer is an
ethylene-vinyl acetate-acrylate copolymer having a methylol group
and/or an alkoxymethyl group as a self-crosslinkable component.
Further, the image transfer layer preferably includes a
self-crosslinkable polymer having a glass transition temperature
(Tg) higher than or equal to 0.degree. C. and a self-crosslinkable
polymer having a glass transition temperature (Tg) lower than
0.degree. C.
Furthermore, the room-temperature vulcanizing silicone rubber and
the self-crosslinkable polymer are preferably aqueous emulsion
types.
In another embodiment of the present invention, an image forming
method is provided in which a toner image is formed on the image
transfer sheet by an electrophotography method and fixed upon
application of at least one of heat and pressure.
In yet another embodiment of the present invention, an image
forming method is provided in which a thermofusible ink image or a
sublimation dye image is formed on the image transfer sheet by a
thermal transfer recording method.
These and other objects, features and advantages of the present
invention will become apparent upon consideration of the following
description of the preferred embodiments of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Generally, the present invention provides an image transfer sheet
in which a releasing layer preferably including a silicone compound
is formed on at least one side of a substrate, a transfer layer
including a self-crosslinkable polymer is formed on the releasing
layer and, if necessary, a back coat layer is formed on the
non-layered side of the substrate and the image forming method
therefor.
The image forming method of the present invention is, for example,
as follows:
(1) an image is formed on the transfer layer with toner, ink, a dye
or the like by an electrophotography method, a thermal transfer
recording method, an ink jet recording method or the like;
(2) an image receiving material is superimposed on the image on the
image transfer sheet;
(3) heat and pressure are applied to the image transfer sheet and
the image receiving material to transfer the image onto the image
receiving material; and
(4) after the image transfer sheet and the image receiving material
are cooled to room temperature, the image transfer sheet is
released from the image receiving material to form the image on the
image receiving material.
The image transfer sheet of the present invention has advantages as
follows:
(1) the image transfer layer has good receivability of a toner, an
ink or a dye image when the image is formed on the image transfer
layer by conventional image forming methods, such as
electrophotography, thermal transfer recording, ink jet recording
or the like;
(2) the image transfer layer easily softens upon application of
heat and pressure and firmly adheres on various image receiving
materials when the image is transferred onto the image receiving
materials;
(3) a high quality image can be formed on the image receiving
materials together with the image transfer layer because the image
transfer sheet can easily be released from the image receiving
materials at the interface of the releasing layer and the image
transfer layer even when the image transfer sheet is cooled to room
temperature; and
(4) the transferred image has good resistance to the heat of an
iron and washing because the transfer layer including a
self-crosslinkable polymer is crosslinked by the effect of the heat
applied for transferring the image.
Suitable materials for use in the releasing layer of the present
invention include waxes, such as polyethylene wax, paraffin wax,
carnauba wax, candelilla wax, rice wax, lanolin wax, ester wax,
oxidized wax, petroleum resin wax, montan wax, bisamide type wax
and microcrystalline wax; higher fatty acids and derivatives
thereof, such as higher fatty acids, higher fatty acid
monoglyceride and higher fatty acid amides; higher aliphatic
alcohols; and resins, such as polyethylene, ethylene-vinyl acetate
copolymers (EVA), polypropylene, alkyd resins, urethane resins,
acrylic resins, polyester resins, fluorine-containing resins,
silicone resins and derivatives thereof. These materials are
employed alone or in combination.
Among these materials, silicone compounds are preferable because of
providing the image transfer sheet with good releasability from the
image receiving material even when the image transfer sheet is
cooled to room temperature after an image is transferred onto the
image receiving material upon application of heat and pressure.
Suitable silicone compounds for use in the releasing layer include
silicone oils, silicone waxes, silicone rubbers, and silicone
resins. Among these silicone compounds, silicone rubbers are
preferable and room-temperature vulcanizing silicone rubbers are
more preferable. The room-temperature vulcanizing silicone rubbers
are preferably aqueous emulsion types to prevent environmental
pollution caused by evaporation of organic solvents and to save a
manufacturing cost. In addition, when the room-temperature
vulcanizing silicone rubbers are used for the releasing layer,
highly crosslinked silicone rubbers are obtained without heating
for crosslinking the releasing layer, resulting in saving a
manufacturing cost. When a highly crosslinked releasing layer is
formed, the image transfer layer can easily release from the
releasing layer when images on the image transfer layer are
transferred onto the image receiving materials because the
releasing layer has sufficiently good heat resistance so as not to
become mixed with the image transfer layer by the effect of the
heat for transferring the images. Therefore, the image transfer
sheet of the present invention can solve the following drawbacks of
conventional image transfer sheets:
(1) a uniform and high quality image cannot be obtained unless the
image transfer sheet is released from an image receiving material
while the image transfer sheet and the image receiving material are
hot; and
(2) when a large image is transferred, a uniform and high quality
image cannot be obtained because the releasability of the image
transfer sheet from the image receiving material is different at
the release start point and the release end point.
The preferred coating weight of the releasing layer is from about
0.05 to about 5.0 g/m.sup.2 on a dry basis to maintain good
releasability of the image transfer sheet from the image receiving
materials.
Suitable self-crosslinkable polymers for use in the image transfer
layer of the image transfer sheet of the present invention include
polymers having a self-crosslinkable group such as, for example,
methylol, alkoxymethyl, carboxyl, epoxy, hydroxy, amide, methylol
modified acrylamide and vinyl. Among these polymers, polymers
having at least one of a methylol group and an alkoxymethyl group
are preferable and ethylene-vinyl acetate-acrylate copolymers
having at least one of a methylol group and an alkoxymethyl group
are more preferable because the image transfer layers including
these polymers have good preserving properties and exhibit good
crosslinking properties when the image transfer sheets are heated
to transfer images. The self-crosslinkable polymers are preferably
aqueous emulsion types to prevent environmental pollution caused by
evaporation of organic solvents and to save a manufacturing
cost.
The preferred crosslinking temperature of the self-crosslinkable
polymer is from about 80 to about 250.degree. C. to maintain good
preserving properties and good crosslinking properties of the image
transfer layer.
The preferred molecular weight of the self-crosslinkable polymer is
from about 10,000 to about 500,000 to maintain good image
fixability. In addition, preferably, both a self-crosslinkable
polymer having a glass transition temperature (Tg) higher than or
equal to 0.degree. C. and a self-crosslinkable polymer having a
glass transition temperature (Tg) lower than 0.degree. C. are
included in the image transfer layer and/or both a
self-crosslinkable polymer having a molecular weight of from about
10,000 to about 500,000 and a self-crosslinkable polymer having a
molecular weight of from about 10,000,000 to about 60,000,000 are
included in the image transfer layer to maintain good image
fixability of the transferred images and good feeding properties of
the transfer sheet in image forming apparatus. The preferred mixing
ratios of a self-crosslinkable polymer having a glass transition
temperature (Tg) higher than or equal to 0.degree. C. to a
self-crosslinkable polymer having a glass transition temperature
(Tg) lower than 0.degree. C. and a self-crosslinkable polymer
having a molecular weight of from about 10,000 to about 500,000 to
a self-crosslinkable polymer having a molecular weight of from
about 10,000,000 to about 60,000,000 are about 1/10to about 10/1by
weight.
The preferred coating weight of the image transfer layer is from
about 5 to about 200 g/m.sup.2 on a dry basis to maintain good
image transferability and good image fixability of the image
transfer sheet.
The image transfer layer of the image transfer sheet of the present
invention may include known materials, such as resins, rubbers or
the like in addition to the self-crosslinkable polymer to control,
for example, flexibility and resistance to rubbing of the image
transfer layer. These materials should be added in an amount that
will not interfere with the good image transferability and
fixability of the image transfer sheet. Specific examples of these
materials include thermoplastic polyurethane resins; polyamide
resins; polyester resins; polyolefin; cellulose derivatives such as
nitrocellulose and cellulose acetate; styrene resins and styrene
copolymers such as polystyrene and poly .alpha.-methyl styrene;
(meth)acrylic resins such as polymethyl (meth)acrylate and
polyethyl (meth)acrylate; vinyl polymers such as vinyl
chloride-vinyl acetate copolymers and ethylene-vinyl acetate
copolymers; rosin ester resins such as rosin and rosin modified
maleic acid resins; natural or synthetic rubbers such as
polyisoprene and styrene-butadiene copolymers; ionomers; epoxy
resins; and phenolic resins.
Thermoplastic polyurethane resins include a polyurethane compound
obtained by the reaction of an isocyanate compound and a polyol
compound having hydroxy groups at the end of the molecule. Specific
examples of the isocyanate compounds include aromatic diisocyanate
compounds, such as tolylene diisocyanate, diphenylmethane-4,
4'-diisocyanate; alicyclic diisocyanate compounds such as
isophorone diisocyanate; and aliphatic diisocyanate compounds, such
as trimethylene diisocyanate, tetramethylene diisocyanate,
hexamethylene diisocyanate and dodecamethylene diisocyanate. The
polyol compounds include polyhydroxy compounds, such as
alkanepolyol, polyesterpolyol and polyetherpolyol. Specific
examples of alkanepolyol include 1,5-pentanediol, 1,8-octanediol,
1,10-decanediol and 1,12-dodecanediol. Specific examples of
polyesterpolyol include, for example, aliphatic polyesterdiol
compounds including at least one of aliphatic diol compounds and
aliphatic dicarboxylic acid compounds which are mentioned later as
a constitutional unit. Specific examples of the polyetherpolyol
include diethylene glycol, triethylene glycol, polyethylene glycol,
tripropylene glycol, polypropylene glycol and adducts of bisphenol
A and an alkylene oxide such as ethylene oxide.
Specific examples of the polyamide resins include nylon 6, nylon
11, nylon 12, nylon 13, nylon 610, nylon 612 and nylon 616.
Specific examples of polyester resins include polyester resins
having at least one of aliphatic diol compounds and aliphatic
dicarboxylic acid compounds as a constitutional unit, and polyester
resins having both of an aliphatic diol compound and an aliphatic
dicarboxylic acid compound are more preferable. Preferably, the
aliphatic carboxylic acid compounds are saturated aliphatic
carboxylic acid compounds. Specific examples of the aliphatic diol
compounds include ethylene glycol, diethylene glycol, triethylene
glycol, polyethylene glycol, propylene glycol, dipropylene glycol,
tripropylene glycol, polypropylene glycol, 1, 3-butanediol, 1,
4-butanediol, neopentyl glycol, 1,6-hexanediol and polymethylene
glycol. Specific examples of the aliphatic carboxylic acid
compounds include saturated aliphatic carboxylic acid compounds,
such as succinic acid anhydride, adipic acid, azelaic acid, sebacic
acid, suberic acid and dodecanedioic acid, and unsaturated
aliphatic carboxylic acid compounds such as maleic acid and fumaric
acid.
Specific examples of the polyolefin include polyethylene such as
low density polyethylene and linear low density polyethylene, and
modified polyolefins, such as ethylene-1-butene copolymers,
ethylene-(4-methyl-1-pentene) copolymers, ethylene-vinyl acetate
copolymers, ethylene-(meth)acrylic acid copolymers,
ethylene-(meth)acrylate copolymers, propylene-1-butene copolymers,
ethylene-propylene copolymers, ethylene-propylene-1-butene
copolymers and olefin-maleic anhydride copolymers. Preferred
polyolefin compounds are the modified polyolefins
above-mentioned.
The image transfer layer of the image transfer sheet of the present
invention may include auxiliary agents, such as tacking agents,
antioxidants, ultraviolet absorbing agents, coloring agents,
antistatic agents, flame retardants, waxes, plasticizers and
fillers.
In addition, the image transfer sheet may include a back coat layer
formed on the non-layered side of the substrate to prevent blocking
of the image transfer sheet when preserved in a relatively high
temperature environment and to obtain good feeding properties of
the image transfer sheet in various image forming apparatus. The
back coat layer preferably has good releasability and relatively
low kinetic friction coefficient in order to obtain the
above-mentioned properties.
Suitable materials useful for the back coat layer include
polyethylene, polypropylene, polyvinyl chloride, polystyrene,
polyvinylidene chloride, acrylonitrile-butadiene-styrene copolymers
(ABS), acrylic resins, acrylonitrile-styrene copolymers (AS),
acrylonitrile-acrylate-styrene (AAS),
acrylonitrile-ethylene-styrene (AES), alkyd resins,
poly-4-methyl-1-pentene, polybutene-1, polyvinylidene fluoride,
polyvinyl fluoride, polycarbonate, polyamides, polyacetal,
polyphenylene oxide, polyesters, polybutylene terephthalate,
polyethylene terephthalate (PET), aromatic polyester resins,
polyphenylene sulfide, polyimides, polysulfone, polyether sulfone,
polyarylate, ethyl cellulose, hydroxy ethyl cellulose (HEC),
hydroxy propyl cellulose, methyl cellulose, cellulose acetate,
cellulose acetate butyrate, nitrocellulose, polyvinyl alcohol
(PVA), polyvinyl acetate, polyvinyl butyral, polyvinyl acetal,
polyvinyl pyrrolidone, polymethyl methacrylate, polyethyl acrylate,
polyacryl amide, polyvinyltoluene, coumarone-indene resin,
polyurethane, silicone modified urethane resins,
fluorine-containing urethane resins and silicone rubbers. Among
these materials, silicone rubbers are preferable and a mixture of a
room-temperature vulcanizing silicone rubber and a silicone resin
is more preferable.
The back coat layer may include auxiliary agents, such as releasing
agents, lubricants and fillers, if necessary.
Specific examples of the auxiliary agents include polyethylene wax,
paraffin wax, carnauba wax, higher fatty acid amides, higher
aliphatic alcohols, organopolysiloxane, surfactants, carboxylic
acids and the derivatives thereof, fluorine-containing resins,
silicone oils, silicone resins, talc, silica, calcium carbonate and
titanium oxide.
The back coat layer is preferably formed using an aqueous coating
liquid and preferred coating weight thereof is from about 0.1
g/m.sup.2 to about 10 g/m.sup.2 on a dry basis.
Suitable materials useful for the substrate of the image transfer
sheet of the present invention include but are not limited to,
paper; synthetic paper; cloth; nonwoven fabric; leather; resin
films, such as polyethyleneterephthalate, cellulose diacetate,
cellulose triacetate, acrylic polymers, cellophane, celluloid,
polyvinyl chloride, polycarbonate, polyimide, polyether sulfone,
polyetheretherketone, polyethylene and polypropylene; metal plates;
metallic foil; or the like. In addition, sheets may also be
employed which are made by combining the above-mentioned materials
and by coating or laminating water-proof materials or
electroconductive materials on the above-mentioned materials. Among
these materials, paper having a basis weight of from about 20 to
about 200 g/m.sup.2 is preferable because of providing good feeding
properties for the transfer sheet in image forming apparatus and
having a relatively low manufacturing cost.
Suitable coating methods for forming the releasing layer, the image
transfer layer and the back coat layer of the present invention
include known coating methods, such as roll coating, blade coating,
wire bar coating, air knife coating, rod coating, hot melt coating
and laminate coating. The image transfer sheet of the present
invention is formed, for example, as follows:
(1)a releasing layer coating liquid is prepared by dissolving,
dispersing or emulsifying the compounds used for the releasing
layer in a solvent such as water or the like;
(2) the prepared releasing layer coating liquid is coated on a
substrate by one of the above-mentioned coating methods and dried
to form a releasing layer on the substrate;
(3) an image transfer layer coating liquid is also prepared, for
example, by the same method as mentioned in (1);
(4) the prepared image transfer layer coating liquid is coated on
the releasing layer by one of the above-mentioned coating methods
and dried to make an image transfer layer; and
(5) a back coat layer coating liquid is also prepared and coated on
the non-layered side of the substrate by the same methods as
mentioned in (1) and (2) to form a back coat layer on the
substrate, if desired.
Suitable image forming methods for use in the present invention by
which an image is formed on the image transfer sheet include known
image forming methods, such as electrophotography, offset printing,
relief printing, plate printing, stencil printing, screen printing,
electrostatic recording, ink jet printing, thermal transfer
recording, sublimation thermal transfer recording, dot matrix
printing and handwriting.
Having generally described this invention, further understanding
can be obtained by reference to certain specific examples which are
provided herein for the purpose of illustration only and are not
intended to be limiting. In the descriptions in the following
examples, the numbers represent weight ratios in parts, unless
otherwise specified.
EXAMPLES
Example 1
The following compounds were mixed to prepare a releasing layer
coating liquid (A). The prepared releasing layer coating liquid (A)
was coated on one side of a substrate of paper having a basis
weight of 104.7 g/m.sup.2 with a wire bar and then dried to form a
releasing layer having a coating weight of 1.7 g/m.sup.2 on a dry
basis.
(Formulation of Releasing Layer Coating Liquid (A))
room-temperature vulcanizing silicone rubber emulsion 10
(SE-1980 Clear, solid content of 45%, manufactured by Dow Corning
Toray Silicone Co., Ltd.)
water 40
The following compounds were mixed to prepare an image transfer
layer coating liquid (A). The prepared image transfer coating
liquid (A) was coated on the releasing layer with a wire bar and
then dried to form an image transfer layer having a coating weight
of 30 g/m.sup.2 on a dry basis. Thus an image transfer sheet was
obtained.
(Formulation of Image Transfer Layer Coating Liquid (A))
methylol-group-containing self-crosslinkable ethylene-vinyl
acetate-acrylate copolymer emulsion 10
(Polysol EF-421, Tg of -21.degree. C., solid content of 45%,
molecular weight of from 100,000 to 200,000, cross-linking
temperature of more than or equal to 120.degree. C., manufactured
by SHOWA HIGHPOLYMER CO., LTD.)
methylol-group-containing self-crosslinkable ethylene-vinyl
acetate-acrylate copolymer emulsion 10
(Polysol EF-250N, Tg of 20.degree. C., solid content of 50%,
molecular weight of from 100,000 to 200,000, cross-linking
temperature of more than or equal to 120.degree. C., manufactured
by SHOWA HIGHPOLYMER CO., LTD.)
A full color image was formed on the image transfer layer of the
obtained image transfer sheet (referred to as image transfer sheet
(a)) using a full color image forming apparatus (PRETER 550,
manufactured by Ricoh Co., Ltd.). The image qualities of the full
color image formed on the image transfer layer were as good as
those of the image formed on the special transfer paper for the
image forming apparatus.
Then white cotton cloth was superimposed on the full color image on
the image transfer sheet (a) and the two sheets were heated with
pressure using a thermal transfer pressing machine (Rotary Press,
manufactured by Mainichi Mark Co., Ltd.) at 160.degree. C. for 15
seconds. After the heating with pressure, a united sheet of the
cotton cloth and the image transfer sheet (a) was taken out from
the thermal transfer pressing machine and cooled to room
temperature, and then the transfer sheet (a) was separated from the
cotton cloth to form the image on the cotton cloth. The image
transfer layer was completely transferred onto the cotton cloth
together with the image and there was no residual image on the
image transfer sheet (a). The transferred image on the cotton cloth
had good image qualities.
The transferred image on the cotton cloth was ironed at a
temperature suitable for pressing cotton cloth. The transferred
image was hardly damaged and also hardly adhered to the iron. The
cotton cloth with transferred image was also washed for 15 minutes,
rinsed and dewatered using a full automatic washer (KW-60R3,
manufactured by Hitachi Ltd.) and dried at room temperature. The
procedure of the washing above-mentioned was repeated 10 times,
however, discoloration or peeling of the image was not
observed.
Example 2
The procedures for preparation and evaluation of the image transfer
sheet in Example 1 were repeated except that the formulation of the
image transfer layer coating liquid was replaced by the following
image transfer layer coating liquid (B) to obtain an image transfer
sheet (b).
(Formulation of Image Transfer Layer Coating Liquid (B))
methylol-group-containing self-crosslinkable ethylene-vinyl
acetate-acrylate copolymer emulsion 10
(Polysol EF-250N, Tg of 20.degree. C., solid content of 50%,
molecular weight of from 100,000 to 200,000, cross-linking
temperature of more than or equal to 120.degree. C., manufactured
by SHOWA HIGHPOLYMER CO., LTD.)
non reactive carbonate type polyurethane
resin emulsion 20
(Super Flex 460, solid content of 38%, Tg of -21.degree. C.,
manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)
The full color image formed on the image transfer layer of the
image transfer sheet (b) by the full color image forming apparatus
had good image qualities and the transferred full color image on
the white cotton cloth had good image qualities and good resistance
to the heat of an iron and washing.
Example 3
The procedures for preparation and evaluation of the image transfer
sheet in Example 1 were repeated except that the formulation of the
image transfer layer coating liquid was replaced by the following
image transfer layer coating liquid (C) to obtain an image transfer
sheet (c) and the pressing time of the thermal transfer pressing
machine was 1 minute.
(Formulation of Image Transfer Layer Coating Liquid (C))
methylol-group-containing self-crosslinkable ethylene-vinyl
acetate-acrylate copolymer emulsion 10
(Polysol EF-421, Tg of -21.degree. C., solid content of 45%,
molecular weight of from 100,000 to 200,000, cross-linking
temperature of more than or equal to 120.degree. C., manufactured
by SHOWA HIGHPOLYMER CO., LTD.)
acrylic acid ester copolymer emulsion 10
(Polysol SUM-1400, Tg of 10.degree. C., solid content of 50%,
molecular weight of 10,000,000, manufactured by SHOWA HIGHPOLYMER
CO., LTD.)
The full color image formed on the image transfer layer of the
image transfer sheet (c) by the full color image forming apparatus
had good image qualities and the transferred full color image on
the white cotton cloth had good image qualities and good resistance
to the heat of an iron and washing.
Example 4
The procedures for preparation and evaluation of the image transfer
sheet in Example 1 were repeated except that the formulation of the
image transfer layer coating liquid was replaced by the following
image transfer layer coating liquid (D) to obtain an image transfer
sheet (d).
(Formulation of Image Transfer Layer Coating Liquid (D))
methylol-group-containing self-crosslinkable acrylic acid ester
copolymer emulsion 10
(Polysol SUM-4002, Tg of -20.degree. C., solid content of 46%,
molecular weight of 50,000,000, cross-linking temperature of more
than or equal to 120.degree. C., manufactured by SHOWA HIGHPOLYMER
CO., LTD.)
methylol-group-containing self-crosslinkable ethylene-vinyl
acetate-acrylate copolymer emulsion 10
(Polysol EF-250N, Tg of 20.degree. C., solid content of 50%,
molecular weight of from 100,000 to 200,000, cross-linking
temperature of more than or equal to 120.degree. C., manufactured
by SHOWA HIGHPOLYMER CO., LTD.)
The full color image formed on the image transfer layer of the
image transfer sheet (d) by the full color image forming apparatus
had good image qualities and the transferred full color image on
the white cotton cloth had good image qualities and good resistance
to the heat of an iron and washing.
Example 5
The procedures for preparation and evaluation of the image transfer
sheet in Example 1 were repeated except that the formulation of the
releasing layer coating liquid was replaced by the following
releasing layer coating liquid (B) to obtain an image transfer
sheet (e).
(Formulation of Releasing Layer Coating Liquid (B))
stearic acid amide emulsion 10 (Himicron G-270, solid content of
21.5%, manufactured by Chukyo Yushi Co., Ltd.)
The image transfer sheet (e) could not be released from the white
cotton cloth after the two sheets of the image transfer sheet and
the cotton cloth were heated by the thermal transfer pressing
machine and cooled to room temperature to transfer an image.
However, the image transfer sheet (e) could easily be released from
the cotton cloth while the two sheets of the image transfer sheet
(e) and the cotton cloth were hot, and the image transfer layer was
completely transferred onto the cotton cloth together with the
image. The transferred image on the cotton cloth had good image
qualities and good resistance to the heat of an iron and
washing.
Comparative Example 1
The procedures for preparation and evaluation of the image transfer
sheet in Example 1 were repeated except that the formulation of the
image transfer layer coating liquid was replaced by the following
image transfer layer coating liquid (E) to obtain an image transfer
sheet (f).
(Formulation of Image Transfer Layer Coating Liquid (E))
ethylene-vinyl acetate copolymer emulsion 10 (Polysol EVA AD-6, Tg
of 3.degree. C., solid content of 56%, manufactured by SHOWA
HIGHPOLYMER CO., LTD.)
The full color image formed on the image transfer layer of the
image transfer sheet (f) by the full color image forming apparatus
had good image qualities and the transferred full color image on
the white cotton cloth had good image qualities. However, the image
was destroyed and a great quantity of the image transfer layer
including the full color toner image was adhered to the iron when
the image transferred cotton cloth was ironed. A part of the
transferred image on the cotton cloth was peeled after one time of
washing.
Comparative Example 2
The procedures for preparation and evaluation of the image transfer
sheet in Comparative Example 1 were repeated except that the
formulation of the releasing layer coating liquid was replaced by
the aforementioned releasing layer coating liquid (B) to obtain an
image transfer sheet (g).
The image transfer sheet (g) could not be released from the white
cotton cloth after the two sheets were cooled to room temperature,
and when the image transfer sheet (g) was forced to release from
the cotton cloth, the image transfer sheet (g) was broken. The
image transfer sheet (g) could be released from the cotton cloth
while the two sheets were hot, however the transferred image had
poor image qualities because a part of the image on the image
transfer sheet (g) remained thereon after the image transfer sheet
(g) was released from the cotton cloth.
As can be understood from the description of Examples 1 to 5 and
Comparative Examples 1 and 2, the image transfer sheets of the
present invention have the following advantages:
(1) the image transfer sheets can be manufactured using aqueous
emulsions, resulting in preventing environmental pollution and
saving manufacturing cost;
(2) the image transfer sheets have good feeding properties in the
image forming apparatus and the formed images on the image transfer
layers have good image qualities;
(3) the images formed on the image transfer sheet are easily and
completely transferred onto the image receiving material even when
the image transfer sheets are cooled to room temperature if the
releasing layers include a silicone compound; and
(4) the transferred image on the image receiving material has good
image qualities and good resistance to heat of iron and
washing.
Additional modifications and variations of the present invention
are possible in light of the above teachings. It is therefore to be
understood that within the scope of the appended claims the
invention may be practiced other than as specifically described
herein.
This application is based on Japanese Patent Application No.
08-135434, filed on May 29, 1996, the entire contents of which are
herein incorporated by reference.
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